Spring is just around the corner and even though I caution folks about planting and seeding too early in the season, truthfully… it’s safe to go ahead and start a few things indoors.

Taking care to read your seed catalogs, choose the varieties that are recommended for your area and be sure to read how long it takes to produce each crop. Some items may not take as long as others. For instance, lettuces can be directly sown into containers and grow quickly in cooler temperatures, yet tomatoes benefit from seeding into one container at a warm temperature, and then transplanted into a larger container to grow a better root system before being put into the ground. Squash, cucumbers and melons are faster crops, and like to be sown later, closer to planting time. Sow multiple seed directly into 3- or 4-inch pots, and then, once developed, directly plant them into the garden.

Reputable seed companies all offer specific information about each type of vegetable or plant they offer. Some companies offer better information than others, and I depend on these as a reference guide. It’s a good idea to check the varieties for how large they grow, for instance; determinate bush tomatoes don’t take as much room as indeterminate vine varieties. Store your seed tightly closed in a refrigerator (not a freezer) when not in use. Many varieties will last for years if stored properly.

This south-facing window is perfect for starting an indoor seeding area.

When wanting to garden indoors or start your plants inside, the first thing to do is dedicate an area just for this purpose. Find a south-facing window if possible because it provides the most light for ensuring healthy starts. If not a south window, select the brightest one you have. You can always move plants away a few feet if it becomes too hot to handle.

You need a sturdy table or two for seeding and related equipment. Anything from a folding card table to a sturdy work bench will do. Cover it with plastic so moisture won’t ruin the surface. Then set up a stand with a fluorescent light fixture or two for your plants after they begin to grow. There are grow lights of all kinds, but fluorescents are cool lights and still provide the wide spectrum necessary to keep seedlings and other plants from stretching. You needn’t turn the lights on yet – wait till right after the seeds germinate. Remember, a leggy plant is not a healthy one, and you might as well purchase new plants or start over if stretching becomes a problem.

Invest in a small sprayer for watering seedlings. You don’t want to pour water from a watering can or it will wash out your soil, cover seeds too much, and cause uneven moisture.

The next thing you need is a heat source under the trays for the root systems to develop. Heating mats made especially for this purpose are available in all sizes and prices. It’s a good investment, especially if you keep your home or growing area cool. The rooting zone of most vegetable and annual seedlings should be 68 to 78 F, and uniform heating is best.

It’s recommended that you begin with a tray that acts as a capturing device for water and does not drain indoors. You can always remove excess water with a sponge if it builds up. This will prevent spills on the floor and furniture and may also help with keeping humidity levels up in the growing area.

Use trays that hold water and place capillary mats in them. Water the capillary mat before placing seeded pots on it. This will help keep humidity levels up and improve drainage.

Place a “capillary mat” in the tray you plan to set your seeded pots in. A capillary mat is a spongy fiber about ¼ inch thick, much like quilt batting. When you water your seeded pots, this mat will wick away excess moisture from some containers while providing it for others. It makes the watering more uniform throughout the system, keeping the plants moist but not wet. Seed that’s germinating will require 100% humidity but don’t like to stay constantly wet. After sowing seeds in your trays, place them on the capillary mat inside the tray that does not have holes in it. Then water in well with a sprayer or spray bottle. A light spray is best, so you don’t flood or wash seed into each other. If you get tired of pumping a spray bottle, you can use a larger volume one that doesn’t require as much work. A 1-gallon sprayer works great. Be sure to wet the capillary mat too, but not soak it to the point of water pooling anywhere.

Sow seeds thinly in your pots, not too crowded. Many seed companies will specify approximately how many seeds per square inch. Overcrowding will result in stretched, unhealthy seedlings. The more room you give them, the better your plants will turn out. Cover seeds with extra mix, only as deep as the seed is in diameter. Small seeds only need a dusting of mix over them while larger seeds like a little more. Be careful not to bury your seeds or they may not come up at all. Be sure to label your seed as you sow with a waterproof pen. You’d be surprised how fast you’ll forget what you sowed!

Use a specialized “seeding mix” avoiding any media with any fertilizer, as this will inhibit germination. Scatter a few seeds and cover lightly with more mix.

After seeding and watering them in, cover the tray with another tray, preferably black or dark in color, balancing it directly on top of the other like a lid. Most seeds like to germinate in total darkness (just check your varieties), and this tray will hold in humidity and shut out light, as well as keeping the warmth in from your heating mat. At this point, I usually cover the seeded trays with a sheet of plastic to “chamber” the trays. This way I know 100% humidity was held underneath for the seeds to germinate more uniformly, without drying around the edges of the trays. Check your seeds a couple of times a day for moisture, being careful not to let them dry out or remain too wet.

Remove the lids on the trays as soon as the first two leaves appear. Keep checking your trays, and as soon as most seeds have germinated, then turn on the lights. Keep the lights a foot or two away from the young plants so they don’t dry out too quickly. As the plants mature you might want to lower the fixture a little closer, being sure to check frequently for drying out or wilting too much. Try not to water in the evening hours since wet foliage overnight is a disease waiting to happen. This extra light not only helps keep plants short and healthy, but also helps to prevent many water-borne diseases and stem-rots.

Cover seed trays and pots with lids, and then cover the area with a sheet of plastic.

When young seedlings are an inch or two tall it’s time to decide whether they will be planted out into the ground, transplanted into larger pots or hardened off for later. Reducing the average temperatures, withholding some water, and yet still maintaining high light conditions will accomplish this “hardening.” You can do this indoors, or take them outside on good days, placing them in a partial-shade location so they don’t “sunburn.” Be sure to bring them back indoors on chilly nights below 57 F.

Divide and transplant your seedlings before they get too crowded. Continue to grow under lights until ready to out into the garden.

CHECKLIST:

• Select seeds that are best suited for your area (zone) or growing needs.
• Construct a table and lighting system.
• Assemble trays that hold water in addition to growing trays.
• Use capillary mats to improve drainage.
• Use a “seeding” mix, avoid any media with added fertilizer.
• Invest in a sprayer for watering seedlings.
• Check growing conditions for each variety before you start.
• Remove any covering as soon as seeds germinate.
• Check your new plants and mist as needed at least twice daily, but avoid watering in the evening hours.

When transplanting young seedlings, the stem is sometimes buried up to the first set of true leaves. Many plants will root out from the stem creating better development and structure. Be careful not to pack soil mixes too tightly around the necks of these young plants as they might bruise easily. Simply sift the soil up around their necks and water in. At this point I choose a weakened, half-dose of water-soluble fertilizer or root stimulator. An organic, water-soluble solution is also a good choice to add beneficial microelements and get them off to a great start. Keep plants under lights until they go outside, and be sure to stay on top of watering needs until established in the garden.

Record keeping is really important if you ever hope to be successful at growing your own plants. Keeping notes of the date sown, plant variety, how many seeds you sowed and when they matured enough to transplant will really help you with timing your crops each year.

A version of this article appeared in a March 2010 print edition of State-by-State Gardening.
Photography courtesy of Rita Randolph.

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